mid-15c., "turned away in mind or feeling, disliking, unwilling," from Old French avers "hostile, antagonistic" and directly from Latin aversus "turned away, turned back," past participle of avertere "to turn away," from ab "off, away from" (see ab-) + vertere "to turn" (see versus). Originally and usually in English in the mental sense, while averted is used in a physical sense.

Averse applies to feeling, adverse to action: as, I was very averse to his going: an adverse vote: adverse fortune. [Century Dictionary, 1906]